This invention relates to the manufacture of poppet valves and has a particularly useful but not exclusive application in the manufacture of poppet valves for use in high performance petrol and diesel engines.
The advent of the high performance petrol and diesel engine has made severe demands on the poppet valve manufacturer. Good performance at ever increasing temperatures coupled with the need for keeping costs to the lowest level have resulted in most valves being composite in nature. Often the head is made of a high performance steel friction welded to a lower cost steel stem or the valve is faced with an expensive oxidation resistant high temperature alloy.